Re: Socket selection.

From: Pawel Jakub Dawidek (pjd_at_FreeBSD.org)
Date: 05/20/04

  • Next message: Dmitri Denissov: "protecting netgraph calls from outside of the network context" 
    Date: Thu, 20 May 2004 23:10:58 +0200
To: Andre Oppermann <andre@freebsd.org>

    On Thu, May 20, 2004 at 11:01:46PM +0200, Andre Oppermann wrote:
    +> Pawel Jakub Dawidek wrote:
    +> >
    +> > Hello.
    +> >
    +> > In in_pcblookup_hash() function, in the last loop if we find exact
    +> > match, we return immediately, if it is "wild", we store a pointer and
    +> > we countinue looking for exact match.
    +> > I wonder if this is ok, that we change pointer every time we find a
    +> > "wild" match. Is it inteded? Shouldn't it be:
    +> >
    +> > http://people.freebsd.org/~pjd/patches/in_pcb.c.2.patch
    +>
    +> No. This is a stack variable which is unconditionally initialized to
    +> NULL a few lines earlier. Checking for variable == NULL is always
    +> going to be true and makes your 'optimization' just redundand.

    But we have loop there:

            local_wild = NULL;
            [...]
            LIST_FOREACH(...) {
                    [...]
                    local_wild = <something>;
                    [...]
            }

    Isn't that possible that local_wild will be set few times?

    +> > While I'm here, I want to improve code readability a bit:
    +> >
    +> > http://people.freebsd.org/~pjd/patches/in_pcb.c.3.patch
    +> >
    +> > Is it ok?
    +>
    +> No. You change the logic of the 'if' statements to something totally
    +> different. This ain't going to work in any way.

    Hmm, no:

    for (...) {
            if (a == b && c == d) {
                    /* do something */
            }
            /* nothing here */
    }

    is equivalent to:

    for (...) {
            if (a != b || c != d)
                    continue;
            /* do something */
    }

    isn't it? 

    -- 
Pawel Jakub Dawidek                       http://www.FreeBSD.org
pjd@FreeBSD.org                           http://garage.freebsd.pl
FreeBSD committer                         Am I Evil? Yes, I Am!

  • Next message: Dmitri Denissov: "protecting netgraph calls from outside of the network context"

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